HP MLIB User's Guide Vol. 1 7th Ed.

Chapter 2 Basic Vector Operations 151
Clear vector SZERO/DZERO/IZERO/CZERO/ZZERO
INTEGER*8 n, incx
COMPLEX*16 x(lenx)
CALL ZZERO(n, x, incx)
Input n Number of elements of vector x to be set to zero. If
n ≤ 0, the subprograms do not reference x.
incx Increment for the array x, incx ≠ 0. x is stored forward
in array x with increment |incx|; that is, x
i
is stored in
x((i−1)×|incx|+1).
Use incx = 1 if the vector x is stored contiguously in
array x; that is, if x
i
is stored in x(i). Refer to “BLAS
Indexing Conventions” in the introduction to this
chapter.
Output x Array of length lenx = (n−1)×|incx|+1 containing the
n-vector x that has been set to zero. If n ≤ 0, then x is
unchanged. Otherwise, x ← 0.
Fortran
Equivalent
SUBROUTINE SZERO (N, X,INCX)
REAL*4 X(*)
IF ( N .LE. 0 ) RETURN
IX = 1
INCXA = ABS ( INCX )
DO 10 I = 1, N
X(IX) = 0.0
IX = IX + INCXA
10 CONTINUE
RETURN
END
Example Zero the REAL*8 vector, where x is a vector 10 elements long stored in a
one-dimensional array X of dimension 20 (compare with “Example 2” in the
description of SCOPY).
INTEGER*4 N,INCX
REAL*8 X(20)
N = 10
INCX = 1
CALL DZERO (N,X,INCX)